1. Field of the Invention
The present invention relates to an image pickup system and, more particularly, to an image pickup system that picks up an image using two lens apparatuses.
2. Description of the Related Art
There is conventionally developed an image pickup system in which two image pickup apparatuses are juxtaposed, and parallax images for right and left eyes are picked up, thereby acquiring a 3D image. The image pickup is performed basically by setting the distance between the image pickup apparatuses for right and left eyes to approximately 65 mm (equivalent to the interpupillary distance). In some cases, however, the image pickup apparatuses cannot be arranged at the desired distance because of an influence of the shape or size of the image pickup apparatus. Against this backdrop, an image pickup system has been developed which performs image pickup by arranging image pickup apparatuses above and behind a half mirror. FIG. 8 is a view showing the outer appearance of the image pickup system. FIG. 8 is a side view. The image pickup system includes lens apparatuses 1A and 1B of the same specifications, cameras 2A and 2B of the same specifications, a half mirror 3, and a camera platform 4 supporting these components. The lens apparatus 1A and the camera 2A are arranged in the horizontal state. A light beam from an object passes through the half mirror 3 and enters the camera 2A through the lens apparatus 1A. The lens apparatus 1B and the camera 2B are arranged in the vertical state. A light beam from an object is reflected by the half mirror 3 and enters the camera 2B through the lens apparatus 1B. For example, the lens apparatus 1A and the camera 2A are used to pick up a right eye image, and the lens apparatus 1B and the camera 2B are used to pick up a left eye image. Such vertical arrangement allows to flexibly adjust the distance between the two image pickup apparatuses on the half mirror surface without any influence of the shape or size of the image pickup apparatus itself.
Additionally, in the two lens apparatuses used in the 3D image pickup system, synchronization control of movable optical members such as a magnification-varying mechanism, a focus adjustment mechanism, and an image stabilization mechanism is performed such that the optical conditions always match each other.
For example, Japanese Patent Application Laid-Open No. H09-127400 discloses a driving apparatus that drives, out of a pair of zoom lenses arranged on the left and right sides, a first zoom lens by operating a zoom switch, and on the other hand, drives a second zoom lens such that its photographing magnification matches that of the first zoom lens. A lens apparatus that drives a movable optical member based on a command signal by an operating member such as a zoom switch is defined as a master lens apparatus. A lens apparatus that drives a movable optical member of its own based on the position of the movable optical member on the master side is defined as a slave lens apparatus.
In the related art disclosed in Japanese Patent Application Laid-Open No. H09-127400, the left and right lens apparatuses can be synchronized for the focal length after the stop of driving. However, they cannot accurately be synchronized during driving. In particular, as described above concerning the related art, when an image pickup system that uses a half mirror and vertically arranges a lens apparatus is employed, the left and right lens apparatuses are set in the horizontal state and the vertical state, respectively, and therefore have different driving characteristics. For example, in the lens apparatus installed in the vertical state, the moving direction of the movable optical member matches the direction of gravity. For this reason, when driving the movable optical member in a direction opposite to the direction of gravity, the load increases, and the driving speed decreases. Hence, when the lens apparatus in the horizontal state is set as the master, and the lens apparatus in the vertical state is set as the slave, a shift is generated between the positions of the movable optical members during driving because the driving speed of the slave is lower than that of the master. A 3D image picked up in this state is very difficult to view and produces fatigue on the observer.
Additionally, in Japanese Patent Application Laid-Open No. H09-127400 described above, the master lens apparatus and the slave lens apparatus are uniquely decided. It is therefore impossible to flexibly change the master-slave relationship based on driving conditions such as a posture, a driving direction, and a driving characteristic unique to a lens.